In an unusual broadside during NBC’s morning hours on Monday, Megyn Kelly blasted Jane Fonda, the 80-year-old Hollywood eminence who has been critical of the NBC host in recent months.

It wasn’t even 10 a.m.

“When she first complained publicly after the program — and repeatedly — I chose to say nothing, as my general philosophy is what other people think of me is none of my business,” Ms. Kelly said, giving NBC viewers a glimpse of her old Fox News persona. “However, Fonda was at it again last week, including right here on NBC, and then again elsewhere. So it’s time to address the ‘poor me’ routine.”

Ms. Kelly had heard enough, telling her viewers that she was not about to listen to Ms. Fonda “on what is and is not appropriate — after all, this is a woman whose name is synonymous with outrage.”

In the final 10 minutes of “Megyn Kelly Today,” she reeled off clip after clip, “Daily Show”-style, of Ms. Fonda talking openly about her plastic surgery in past interviews.

“Fonda was on to promote a film about aging,” Ms. Kelly said. “For years she has spoken openly about her joy in giving a cultural face to older women. Well, the truth is, most older women look nothing like Fonda, who is now 80.”

Ms. Kelly also invoked Ms. Fonda’s nickname from the cultural wars of five decades ago — “Hanoi Jane” — adding that it had been bestowed upon the actress because she had tried to “shame American troops.”

Photo

Jane Fonda appeared on the show in September and seemed thrown by a question about her cosmetic surgeries.Credit
Kevin Winter/Getty Images

“By the way, she still says she’s not proud of America,” Ms. Kelly said. “So the moral indignation is a little much. She put her plastic surgery out there. She said she wanted to discuss the plight of older women in America. And, honestly, she has no business lecturing anyone on what qualifies as offensive.”

At 9 p.m. on Fox News, where Ms. Kelly made herself into a household name before leaving the cable network for NBC a year ago, such a contretemps would have come and gone. But in the typically warmer and chattier environs of “Today,” where Hollywood goes to plug its wares, Ms. Kelly’s rebuke of a major celebrity stood out and suggested that NBC’s 9 a.m. hour had undergone a change.

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The host has found some ratings momentum lately by remaking “Megyn Kelly Today” into a forum for discussions of workplace sexual misconduct. The ratings for the hour are up 22 percent in total viewers from the number of people who tuned in back in October, and her audience totals last week — averaging 2.9 million — are the highest they have been during her four months on NBC.

Ms. Kelly has benefited from the longest ratings winning streak for the first two hours of “Today” in nearly six years — a run that has come after the network fired its former star host, Matt Lauer, after he was accused of inappropriate sexual behavior with a subordinate.

When much of the NBC News and Sports divisions fly off to Pyeongchang, South Korea, for the Olympic Games in the coming weeks, Ms. Kelly will remain stateside. NBC News executives have said they do not want to disrupt her momentum. The former “Today” anchor Katie Couric will return to the network as a special guest star, hosting the opening ceremony along with the NBC sportscaster Mike Tirico.

Next week, Ms. Kelly will be dispatched to Washington for NBC’s coverage of the State of the Union address, where she will join correspondents like Lester Holt, Chuck Todd, Tom Brokaw, Andrea Mitchell and Ms. Guthrie.

Ms. Kelly’s on-air criticism of Ms. Fonda occurred days after a report surfaced that a former “Megyn Kelly Today” employee described her show as a “toxic” workplace. NBC called the charges “unfair.”

Representatives for Ms. Fonda did not immediately respond to a request for comment.

A version of this article appears in print on January 23, 2018, on Page B3 of the New York edition with the headline: In Echo of Fox Days, Kelly Lashes Back at Fonda. Order Reprints|Today's Paper|Subscribe